Why do we see an imaginary patch of water (mirage) on the road ahead?

Ah, summertime. Season of cookouts, fireworks, road trips, and mirages . . . like that cool, shimmering pool of water on the highway ahead on a scorching-hot, drought-dry day. Mirages can be even more spectacular in Earth’s coldest regions. Take a trip to the Arctic, and if conditions are just right, you may see an upside-down iceberg, seemingly hanging in the air above the sea.